Those Fat Boy style expansion tubes were custom designed for Aspire Cleito Atomizers: Stainless & Black.
Each tube holds 5.0ml ejuice at most.

Vapor Edge also carries 3.5ml glass tube for Cleito atomizers for your choices.

Brand: Aspire
Unit: 1pc
Material: Pyrex glass
Capacity: 5.0ml
Color: Clear
Shipping weight: 32g
Package: Simple